The entire disclosure of Japanese Patent Application No. 2007-319815, filed Dec. 11, 2007 and Japanese Patent Application No. 2008-222047, filed Aug. 29, 2008, are expressly incorporated herein by reference.
1. Technical Field
The present invention relates to a liquid supply device that supplies a liquid from an upstream side as a liquid supply source side to a downstream side, on which the liquid is consumed, and a liquid ejecting apparatus.
2. Related Art
An ink jet printer (hereinafter, simply referred to as “printer”) is a known example of a liquid ejecting apparatus for ejecting a liquid onto a target. This printer ejects ink (liquid), which is supplied to a recording head (liquid ejecting head), from nozzles formed in the recording head, thereby performing printing on a recording medium as the target. In recent years, as described in JP-A-2006-272661, a printer is suggested in which a pump is provided in an ink flow channel connecting an ink cartridge (liquid supply source) and the recording head to pump ink in order to pressurize and supply ink from the ink cartridge to the recording head.
That is, in the printer described in JP-A-2006-272661, a part of the ink flow channel forms a pump chamber of the pump, and the pump chamber is provided with an ink inlet port that introduces ink from the ink cartridge, and an ink outlet port that discharges ink to the recording head. One-way valves are individually provided in the ink flow channel between the ink cartridge and the ink inlet port and between the recording head and the ink outlet port to permit ink to flow only in a direction from an upstream side toward a downstream side, that is, from the ink cartridge toward the recording head. If the pump performs a suction action, negative pressure is applied to the pump chamber, and accordingly ink is sucked into the pump chamber from the ink cartridge. Ink is supplied to the recording head in a pressurized state in accordance with an ejection action of the pump.
In the printer of JP-A-2006-272661, the negative pressure is generated by the suction action of the pump, and causes ink to be sucked into the pump chamber through the ink flow channel. The negative pressure is applied to the ink flow channel on a downstream side from the pump chamber, as well as the ink flow channel on the upstream side. For this reason, while the pump performs the suction action, the negative pressure toward the upstream side is applied to ink in the ink flow channel on a downstream side from the pump. Accordingly, ink may not be supplied to the recording head on the downstream side in a pressurized state. As a result, in the printer in which the pump is provided in the ink flow channel connecting the ink cartridge and the recording head, during the pump action, ink for printing may not be ejected from the recording head for a moment.